adj
effective
ih-FEHK-tihv
adj
1
Producing the intended result; actually working.
"The new medication proved effective against the infection."
"Regular practice is the most effective way to learn a language."
2
Officially in force or operation as of a stated time.
"The new rules are effective from next Monday."
How to Use Effective
Learner’s notesIn plain EnglishSomething that works, gets the job done, or (for rules/dates) officially starts applying.
Common mistake
Effective means it produces the desired result; efficient means it does so without wasting time, effort, or resources. A plan can be effective but very inefficient.
Easily confused with
Common pairings
effective immediately
highly effective
cost-effective
Word Forms
more effective comparative, effectives plural, most effective superlative
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The new medication proved _____ against the infection.
Etymology
From French effectif, based on Latin efficere, "to bring about" or "accomplish" — the same root that gives us "effect" and "efficient."